Fluid pressure operated switches are used in a variety of applications. Some of the most common applications include control of water pumping and pressurization systems and air compressors.
In the former, as typified by many home water systems supplied by well water, a submersible pump is operative to elevate water to a sealed reservoir or tank. Because the tank is sealed, as it fills, the pressure of air above the water in the tank increases. This pressure head is used to drive water from the tank into the distribution system within the home when faucets or valves are opened. Check valves are utilized to prevent such pressure from driving the water back into the well.
Quite typically, the pressure within the reservoir is taken as a measure of the degree of filling thereof. Most usually, pressure is monitored at a tank outlet which will be below the level of water in the reservoir by means of a water pressure sensing switch which in turn is operative to initiate operation of the pump when pressure is low and to halt operation of the pump when pressure is raised to a level indicating that the reservoir has been sufficiently filled.
In air compressor systems, switch operation is generally similar save for the fact the switches are not coupled to liquid under pressure, but rather, to air under pressure.
In either case, these switch systems include some sort of mechanical coupling by means of a conduit to the source of fluid under pressure that is to be monitored. In addition, the electrical side of the switches will frequently be rigidly connected to an electrical conduit containing the electrical conductors forming part of the circuit which is being controlled by the switch. Pressure sensing in such switches is normally accomplished by diaphragms of one sort or another and experience has illustrated that, when properly designed, the diaphragms in switches of this type are relatively failure free and do not readily wear out.
In contrast, as is well known, the making and breaking of electrical circuits by contacts exposed to air causes progressive deterioration of the contacts to the point where ultimately they cannot establish or break the electrical circuit in which they are contained.
When this occurs with fluid a pressure operated switch, it has been the rule to remove the switch from the system and discard the same, installing a whole new switch in lieu thereof. This, of course, requires that the fluid containing conduit be disconnected from the switch as well as the freeing of the switch from electrical conduits. Where liquid pressure is being monitored, disconnection of the fluid conduit from the switch will result in spillage of the liquid which must be cleaned up and in all events, considerable manual effort may be expended in disconnecting the fluid conduit from the switch as well as disconnecting electrical conduits from the switch.
The present invention is directed to overcoming the above problems.